In recent years, it has become common that an internal-combustion engine (hereinafter, referred to as an “engine” as appropriate) of a vehicle including at least a large-size motorcycle is controlled by an electronic control apparatus provided with a computer.
In the electronic control apparatus of the engine, various kinds of sensors to always detect an operational state and intake-air state of the engine are disposed in the engine and its peripheral apparatuses, and an ECU (Electronic Control Unit) that performs electronic concentrated engine control performs optimal control of the engine based on a variety of data sent from the various kinds of sensors.
In the engine, fuel such as gasoline and air are mixed, and this air mixed fuel is burned in a piston to produce torque, and therefore, optimization is important for intake-air flow rate control as well as fuel supply quantity control of the engine.
An intake-air flow rate to supply air to the engine is adjusted by a throttle apparatus provided on an inlet pipe side connected to the engine. The throttle apparatus is generally comprised of an intake-air cylindrical pipe provided with a throttle valve therein, and the intake-air flow rate is adjusted by adjusting an opening angle of the throttle valve (hereinafter, referred to as simply “throttle”).
Accordingly, the ECU needs to always detect an opening angle of the throttle in the intake-air throttle apparatus with accuracy, and detection of this throttle opening angle is performed based on an output signal of a throttle position sensor (hereinafter, referred to as “TPS”) disposed near the throttle.
The TPS is broadly divided into two types, a contact type and non-contact type. In the contact type, a potentiometer is installed to gear to an operation of a throttle, and a contact member is brought into contact with a resistant film, and thus a throttle opening angle is detected. In the non-contact type, a throttle opening angle is detected using a Hall element or MR element that is not in direct contact with a movable member gearing to the throttle.
The contact type TPS using the potentiometer requires high positioning precision when installed to a throttle body. In other words, after temporarily installing the TPS to a body of the throttle apparatus, it is necessary to adjust a position in the vicinity of a throttle axle while monitoring a signal output from the TPS (for example, see Patent Document JP H11-223508). Such an adjustment needs to be performed for each throttle body in a case of a multi-cylinder engine, and an assembling operation becomes extremely complicated. Further, it is necessary to install a plurality of sensors such as an intake-air temperature sensor and intake-air pressure sensor besides the TPS on an inlet pipe side of the engine, and operation for installing these sensors individually is complicated and reduces operational efficiency.
Hence, there are proposed a sensor integrated throttle body where the non-contact type TPS is used that does not require such complicated installing operation and adjustment, and is integrally installed to a throttle body together with other sensors (for example, see Patent Document JP H09-250374), and an installation structure where an ECU substrate, on which a plurality of sensors are assembled, is installed in a throttle body (for example, see Patent Document JP H11-294216).
However, in the sensor integrated throttle body as described in Patent Document JP H09-250374, since the throttle body itself serves as sensor mounting structure on which a plurality of sensors are mounted, there are provided large limitations on size of the throttle apparatus and internal and external shapes of the throttle body, and production cost is thus increased. Further, since each sensor is installed individually to a predetermined portion of the throttle body, installation operational efficiency is not improved greatly in a production process as compared to a conventional sensor installation method.
Further, in a method of installing an ECU substrate, on which a plurality of sensors are mounted, in a throttle body as disclosed in Patent Document JP H11-294216, the method contributes to reduction in operation of wiring between the sensors and ECU substrate, but imposes large limitations not only on size of the throttle apparatus and internal and external shapes of the throttle body, but also on size of the ECU substrate and arrangement positions of electric components on the substrate. Therefore, particularly, it is sometimes difficult to mount such a substrate on a small-size throttle apparatus for a two-wheel motorcycle or compact-sized car.
It is an object of the present invention to provide a sensor installation structure which remarkably facilitates installation of a plurality of sensors arranged on an inlet pipe side of an engine, enables each of the sensors to be positioned in an accurate measuring position, and does not need to impose large limitations on size and shape of an apparatus targeted for installation of the sensors.